IntraMessenger is a special instant messenger, can authenticate (login+password) through many forums.
Client (only under Windows for the moment) screenshot:
To active external authentication, select your forum in list:
Server screenshots - Client screenshots - Admin control panel live demonstration
Indeed, that's a nice extension!
FSR Admin - Vote for 2012.
Thanks for providing the screenshots. Is there any demo link for this extension.
Community Forum Software by Helprace